Users of modern information systems are subject to exposure to quantities of many information objects, such as electronic mail (also referred to as emails), wiki articles, calendar invitations, microblog posts, etc. This may result in flood (i.e., too much information) and scatter (i.e., too many repositories and sources of information). Modern systems attempt to help users find their way through the data barrage by giving the users ways to organize information, to reduce the amount the users see at any one time, etc.
Some conventional systems assess and concentrate on one or more properties of the information object and organize on instances of the property. An example of this is sorting emails by date, where the date and the email type are the selected properties. Tag (topic) clouds and people's organizational hierarchies are other examples. The user's exposure to the information objects depends on which properties the user, or the system, selects to expose to the user.